I would definitely morph Humans, and maybe also steal some dracon beams for later use. I may not use them very often, but if there was ever an occassion where we could transport them to an area, then I would. especilly since in real life I wouldn't have plot armor, and my enemies wouldn't be graduates of the Stormtroopers Marksmen academy. If you know what I mean.
I would also get some distance flyers early on, so we don't have to go over how often we need to rest during long flights, and how we have to stay far apart from each other. That wouldn't happen because we would be geese, or some other flock bird that can fly great distances without tiring.
If the Chee are there then I'd have them start covering for us a lot sooner. Like starting in book 11. I would also use the box to increase our numbers, but try to never let the Yeerk see more than six of us at once. We don't need to let them know that we are expanding, or how many of us there actually are. There could be a hundred auxilaries, but the Yeerks wouldn't know unless they captured one alive. And we would use Ax and the Chee to ensure the auxilaries are kept mostly in the dark.